Vapor phase thermal etch solutions for metal oxo photoresists

ABSTRACT

Embodiments disclosed herein include methods of developing a metal oxo photoresist. In an embodiment, the method comprises providing a substrate with the metal oxo photoresist into a vacuum chamber, where the metal oxo photoresist comprises exposed regions and unexposed regions. In an embodiment, the unexposed regions comprise a higher carbon concentration than the exposed regions. The method may further comprise vaporizing a halogenating agent into the vacuum chamber, where the halogenating agent reacts with either the unexposed regions or the exposed regions to produce a volatile byproduct. In an embodiment, the method may further comprise purging the vacuum chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.18/116,556, filed on Mar. 2, 2023, which is a continuation of U.S.patent application Ser. No. 17/348,589, filed on Jun. 15, 2021, whichclaims the benefit of U.S. Provisional Application No. 63/047,157, filedon Jul. 1, 2020, the entire contents of which are hereby incorporated byreference herein.

BACKGROUND 1) Field

Embodiments of the present disclosure pertain to the field ofsemiconductor processing and, in particular, to methods of developing ametal oxo photoresist using vapor phase processes.

2) Description pf Related Art

Lithography has been used in the semiconductor industry for decades forcreating 2D and 3D patterns in microelectronic devices. The lithographyprocess involves spin-on deposition of a film (photoresist), irradiationof the film with a selected pattern by an energy source (exposure), andremoval (etch) of exposed (positive tone) or non-exposed (negative tone)region of the film by dissolving in a solvent. A bake will be carriedout to drive off remaining solvent.

The photoresist should be a radiation sensitive material and uponirradiation a chemical transformation occurs in the exposed part of thefilm which enables a change in solubility between exposed andnon-exposed regions. Using this solubility change, either exposed ornon-exposed regions of the photoresist is removed (etched). Now thephotoresist is developed and the pattern can be transferred to theunderlying thin film or substrate by etching. After the pattern istransferred, the residual photoresist is removed and repeating thisprocess many times can give 2D and 3D structures to be used inmicroelectronic devices.

Several properties are important in lithography processes. Suchimportant properties include sensitivity, resolution, lower line-edgeroughness (LER), etch resistance, and ability to form thinner layers.When the sensitivity is higher, the energy required to change thesolubility of the as-deposited film is lower. This enables higherefficiency in the lithographic process. Resolution and LER determine hownarrow features can be achieved by the lithographic process. Higher etchresistant materials are required for pattern transferring to form deepstructures. Higher etch resistant materials also enable thinner films.Thinner films increase the efficiency of the lithographic process.

SUMMARY

Embodiments disclosed herein include methods of developing a metal oxophotoresist. In an embodiment, the method comprises providing asubstrate with the metal oxo photoresist into a vacuum chamber, wherethe metal oxo photoresist comprises exposed regions and unexposedregions. In an embodiment, the unexposed regions comprise a highercarbon concentration than the exposed regions. The method may furthercomprise vaporizing a halogenating agent into the vacuum chamber, wherethe halogenating agent reacts with either the unexposed regions or theexposed regions to produce a volatile byproduct. In an embodiment, themethod may further comprise purging the vacuum chamber.

A method of developing a metal oxo photoresist may also comprise,providing a substrate with the metal oxo photoresist into a vacuumchamber, where the metal oxo photoresist comprises exposed regions andunexposed regions. In an embodiment, the unexposed regions comprise ahigher carbon concentration than the exposed regions. The method mayfurther comprise vaporizing a halogenating agent into the vacuumchamber, where the halogenating agent reacts with either the unexposedregions or the exposed regions to produce a non-volatile product. In anembodiment, the method may further comprise vaporizing a ligand into thevacuum chamber, where the ligand reacts with the non-volatile product toproduce a volatile byproduct. In an embodiment, the method may furthercomprise purging the vacuum chamber.

A method of developing a metal oxo photoresist may also comprise,providing a substrate with the metal oxo photoresist into a vacuumchamber, where the metal oxo photoresist comprises exposed regions andunexposed regions. In an embodiment, the unexposed regions comprise ahigher carbon concentration than the exposed regions. The method mayfurther comprise vaporizing an organic acid into the vacuum chamber,where the organic acid reacts with either the unexposed regions or theexposed regions to produce a volatile byproduct. In an embodiment, themethod may further comprise purging the vacuum chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart describing a process for developing a metal oxophotoresist using a vapor phase process with a halogenating agent, inaccordance with an embodiment of the present disclosure.

FIGS. 2A-2C are cross-sectional illustrations of a substrate and aphotoresist depicting operations in the flowchart of FIG. 1 , inaccordance with an embodiment of the present disclosure.

FIG. 3 is a flowchart describing a process for developing a metal oxophotoresist using a vapor phase process with a halogenating agent and aprotonated ligand, in accordance with an embodiment of the presentdisclosure.

FIGS. 4A-4C are cross-sectional illustrations of a substrate and aphotoresist depicting operations in the flowchart of FIG. 3 , inaccordance with an embodiment of the present disclosure.

FIG. 5 is a flowchart describing a process for developing a metal oxophotoresist using a vapor phase process with an organic acid, inaccordance with an embodiment of the present disclosure.

FIG. 6A and 6B are cross-sectional illustrations of a substrate and aphotoresist depicting operations in the flowchart of FIG. 5 , inaccordance with an embodiment of the present disclosure.

FIG. 7 is a cross-sectional illustration of a processing tool that maybe used to implement portions of the process in FIG. 1 , FIG. 3 , orFIG. 5 , in accordance with an embodiment of the present disclosure.

FIG. 8 illustrates a block diagram of an exemplary computer system, inaccordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Methods of developing a metal oxo photoresist using vapor phaseprocesses are described herein. In the following description, numerousspecific details are set forth, such as thermal vapor phase processesand material regimes for developing photoresist, in order to provide athorough understanding of embodiments of the present disclosure. It willbe apparent to one skilled in the art that embodiments of the presentdisclosure may be practiced without these specific details. In otherinstances, well-known aspects, such as integrated circuit fabrication,are not described in detail in order to not unnecessarily obscureembodiments of the present disclosure. Furthermore, it is to beunderstood that the various embodiments shown in the Figures areillustrative representations and are not necessarily drawn to scale.

To provide context, photoresist systems used in extreme ultraviolet(EUV) lithography suffer from low efficiency. That is, existingphotoresist material systems for EUV lithography require high dosages inorder to provide the needed solubility switch that allows for developingthe photoresist material. Organic-inorganic hybrid materials (e.g.,metal oxo materials systems) have been proposed as a material system forEUV lithography due to the increased sensitivity to EUV radiation. Suchmaterial systems typically comprise a metal (e.g., Sn, Hf, Zr, etc.),oxygen, and carbon. Metal oxo based organic-inorganic hybrid materialshave also been shown to provide lower LER and higher resolution, whichare required characteristics for forming narrow features.

In a metal oxo photoresist system, exposure to EUV radiation results inthe removal of carbon. The difference in the carbon percentage betweenthe exposed regions and the unexposed regions is used as the solubilityswitch during developing. Particularly, the unexposed regions with thehigher carbon content are preferentially etched by the developersolution in a negative tone develop.

Metal oxo photoresist systems are currently developed using a wetchemistry. That is, after exposure, the unexposed regions of thephotoresist are developed by organic solvents/base solution that is usedwith spin-dry process. A post-bake anneal may also be included. However,wet methods can be troublesome when dealing with high aspect ratiofeatures due to the risk of pattern collapse (especially in line orpillar structures). Additionally, wet processes might not remove all ofthe material that is supposed to be removed and filmmaterials/byproducts/solvents and the like may be trapped in smallfeatures.

Accordingly, embodiments of the present disclosure provide a vapor phasethermal etching process to develop metal oxo photoresists. Particularly,vapor phase thermal etching processes provide the advantages of: 1)eliminating the generation of wet byproducts; 2) providing fewer defectsand impurities; 3) lower waste streams due to dry chemistry beingdestroyed in an abatement system; 4) improvement of LER; and 5) lessdamage with dry thermal etch when compared to plasma damage in reactiveion etching (RIE). For example, at a pitch less than 30 nm (e.g., lineCD less than 14 nm) and less than 15 nm photoresist thickness, a plasmacan potentially damage the photoresist mask which may result in poorLER/LWR or even a broken line pattern when the pattern is transferred tothe underlayer.

Embodiments disclosed herein provide various vapor phase thermal etchingprocesses that are executed after portions of a metal oxo photoresistare exposed with a suitable electromagnetic radiation source (e.g., anEUV source). In a first embodiment, the vapor phase thermal etchingprocess includes vaporizing a halogenating agent into a vacuum chamber.The halogenating agent reacts with either the unexposed or exposedregions of the photoresist to produce a volatile byproduct that isremoved from the vacuum chamber. In a second embodiment, the vapor phasethermal etching process includes vaporizing a halogenating agent into avacuum chamber. The halogenating agent may react with either theunexposed or exposed regions of the photoresist to produce anon-volatile product. A ligand may then be vaporized into the chamber,and the ligand reacts with the non-volatile product to provide avolatile byproduct that can be removed from the vacuum chamber. In athird embodiment, the vapor phase thermal etching process includesvaporizing an organic acid into a vacuum chamber. The organic acidreacts with either the unexposed or exposed regions of the photoresistto produce a volatile byproduct that is removed from the vacuum chamber.

Referring now to FIG. 1 , a flowchart illustrating a process 120 fordeveloping a metal oxo photoresist on a substrate surface is provided,in accordance with an embodiment of the present disclosure. FIGS. 2A-2Care cross-sectional illustrations of a substrate 261 and a metal oxophotoresist 262 after various operations in process 120.

In an embodiment, process 120 may begin with operation 121 whichcomprises providing a substrate with a metal oxo photoresist. FIG. 2A isa cross-sectional illustration of a substrate 261 with a metal oxophotoresist 262 disposed over a surface of the substrate 261. In anembodiment, the substrate 261 may comprise any substrate material ormaterials typical of semiconductor manufacturing environments. Forexample, the substrate 261 may comprise a semiconducting material.Substrate 261 may comprise semiconductor devices or portions ofsemiconductor devices. Examples of such semiconductor devices include,but are not limited to, memory devices or complimentarymetal-oxide-semiconductor (CMOS) transistors fabricated in a siliconsubstrate and encased in a dielectric layer. The substrate 261 may alsocomprise a plurality of metal interconnects formed above the devices ortransistors, and in surrounding dielectric layers, and may be used toelectrically couple the devices or transistors to form integratedcircuits. In an embodiment, the substrate 261 may be a wafer.

In an embodiment, the metal oxo photoresist 262 (also referred to simplyas “photoresist 262”), may be any metal oxo material system. Suchmaterial systems typically comprise a metal (e.g., Sn, Hf, Zr, etc.),oxygen, and carbon. In a particular embodiment, the photoresist 262,comprises SnOC.

The photoresist 262 may be disposed over the surface of the substrate261 using any suitable deposition process. In an embodiment, thephotoresist is disposed on the surface of the substrate 261 with a wetchemistry using a spin-on process. In an alternative embodiment, thephotoresist is disposed on the surface of the substrate 261 using avapor phase process (i.e., a dry process). In a vapor phase process, ametal precursor and an oxidant may be vaporized to a vacuum chamber,with the metal precursor and the oxidant reacting to deposit a metal oxophotoresist 262 on the surface of the substrate 261. Such dry processesmay be characterized as a chemical vapor deposition (CVD) process, anatomic layer deposition (ALD) process, a plasma enhanced CVD (PE-CVD)process, or a plasma enhanced ALD (PE-ALD) process.

In an embodiment, process 120 may continue with operation 122 whichcomprises exposing portions of the metal oxo photoresist to createexposed regions and unexposed regions. FIG. 2B is a cross-sectionalillustration depicting the exposure process. As shown, electromagneticradiation 264 passes through a mask 263 to expose the exposed regions262 _(E). The unexposed regions 262 _(U) are blocked from theelectromagnetic radiation by the mask 263. In an embodiment, theelectromagnetic radiation is EUV radiation. When EUV radiation is used,the EUV radiation 264 may be reflected off the mask instead of passingthrough the mask. While EUV radiation specifically disclosed herein, itis to be appreciated that any suitable wavelength of electromagneticradiation that can initiate a solubility switch in the metal oxophotoresist 262 may be used. For example, DUV radiation may be used insome embodiments.

In an embodiment, the solubility switch is provided by the loss ofcarbon. Particularly, the exposure to electromagnetic radiation resultsin the removal of carbon from the exposed regions 262 _(E). The highercarbon content in the unexposed regions 262 _(U) renders the unexposedregions more susceptible to etching in the subsequent vapor phasedevelopment process.

In an embodiment, process 120 may continue with operation 123 whichcomprises placing the substrate into a vacuum chamber. In an embodiment,the vacuum chamber may be any suitable chamber for providingsub-atmospheric pressure conditions. The vacuum chamber may also includeheating/cooling features to provide thermal control of the vapor phaseprocess. For example, a pedestal on which the substrate 261 is placedmay be an actively heated and/or cooled pedestal. Additionally, walls ofthe vacuum chamber may be actively heated and/or cooled in someembodiments.

Particularly, it is to be appreciated that embodiments disclosed hereindo not require a plasma source in order to implement the vapor phaseetching of the metal oxo photoresist. Accordingly, the construction ofthe vacuum chamber may be simplified compared to processes that includeplasma based developing of the metal oxo photoresist. A more detaileddescription of a suitable vacuum chamber is provided below with respectto FIG. 7 .

In an embodiment, process 120 may continue with operation 124 whichcomprises vaporizing a halogenating agent into the vacuum chamber. In anembodiment, the halogenating agent reacts with the unexposed regions 262_(U) to produce a volatile byproduct. That is, the reaction between thehalogenating agent and the unexposed regions 262 _(U) results in theremoval of the unexposed regions 262 _(U) from the substrate 261, asshown in FIG. 2C. In other embodiments, the halogenating agent may reactwith the exposed regions 262 _(E) to produce a volatile byproduct. In anembodiment, the byproduct of the reaction is a volatile metal halide.Some metal halides have higher volatilities than others. For exampleSnCl₄ has a higher volatility than SnCl₂, CoClL (where L is a ligand)has a higher volatility than CoCl₂, and MoOCl₄ has a higher volatilitythan MoCl₅. Accordingly, the reaction may preferentially result in theformation of byproducts with higher volatilities. In an embodiment thebyproducts may have the chemical formula MX_(x) or MO_(y)X_(x), where Mis a metal or semimetal, X is a halide, x is 1-6 and y is 1-5.

In an embodiment, the halogenating agent is a metal halide with aformula MX_(a) or MX_(a)L_(b), where M is a metal or semimetal (e.g.,Mo, W, Ta, Nb, Sn, V, Ti, or Si), X is a halide (e.g., Cl or Br), L is avolatile ligand (e.g., alkyls, ethylenediamine, or Cp), a is 1-6 and bis 1-5. For example, the metal halide may comprise MoCl₅, TaCl₅, NbCl₅or WCl₅.

In an additional embodiment, the halogenating agent is a metal oxyhalide with a formula MO_(a)X_(b) or MO_(a)X_(b)L_(c), where M is ametal or semimetal (e.g., Mo, W, Ta, Nb, Sn, V, Ti, or Si), X is ahalide (e.g., Cl or Br), L is a volatile ligand (e.g., alkylsethylenediamine, or Cp), a is 1-5, b is 1-5, and c is 1-5. For example,the metal oxy halide may comprise MoOCl₄, MoO₂Cl₂, WOCl₄, or WO₂Cl₂.

In yet another additional embodiment, the halogenating agent may be anorganic halogenating agent. For example, the halogenating agent maycomprise thionyl chloride (SOCl₂), methanesulfonyl chloride (CH₃SO₂Cl),trichloromethanesulfonyl chloride (CCl₃SO₂Cl), 4-toluenesulfonylchloride (tosyl chloride), oxalyl chloride (ClCOCOCl), tert-butylhypochlorite ((CH₃)₃COCl), N-chlorophthalimide,1,3-dichloro-5,5-dimethylhydantoin, trimethylsilyl chloride, HCl, Cl₂,PCl₅, BCl₃, HBr, Br₂, CCl₃Br, CBr₄,1,2-dibromo-1,1,2,2-tetrachloroethane (Cl₂CBrCBrCl₂), BBr₃, PBr₃,N-bromosuccinimide, N-bromoacetamide,2-bromo-2-cyano-N,N-dimethylacetamide,1,3-dibromo-5,5-dimethylhydantoin,2,4,4,6-tetrabromo-2,5-cyclohexadienone, or trimethylsilyl bromide.

In yet another embodiment, the halogenating agent may comprise one ormore of SOBr₂ (thionyl bromide), SO₂Cl₂ (sulfuryl chloride), and SO₂Br₂(sulfuryl bromide).

In an embodiment, the halogenating agent may be diluted with an inertgas. For example, inert gases such as Ar, N₂, or He may be used todilute the halogenating agent. Generally, it has been shown that theetch selectivity of the unexposed regions of the photoresist 262 _(U)relative to the exposed regions of the photoresist 262 _(E) increaseswith increases in pressure. In an embodiment, the pressure may bebetween approximately 1 torr and approximately 100 torr. In a particularembodiment, the pressure may be between approximately 3 torr andapproximately 10 torr.

In an embodiment, the substrate 261 may have a controlled temperatureduring operation 124. For example, the temperature may vary betweenapproximately 0° C. and approximately 500° C. In a particularembodiment, the temperature may vary between approximately 50° C. andapproximately 200° C. Generally, it has been shown that increasedsubstrate temperatures provide an increase in the etch selectivity ofthe unexposed regions of the photoresist 262 _(U) relative to theexposed regions of the photoresist 262 _(E).

In an embodiment process 120 may continue with operation 125 whichcomprises purging the vacuum chamber. Purging the vacuum chamber removesthe byproducts from the reaction in operation 124 from the vacuumchamber. In an embodiment, operation 124 may be implemented as a soakfollowed by a single purge in operation 125. In alternative embodiments,operations 124 and 125 may define a cycle comprising a pulse of thehalogenating agent followed by a purge. In such embodiments, a pluralityof cycles may be repeated in order to clear the unexposed regions of thephotoresist 262 _(U).

Referring now to FIG. 3 , a flowchart describing a process 330 forpatterning a metal oxo photoresist is shown, in accordance with anembodiment of the present disclosure. FIGS. 4A-4C are correspondingcross-sectional illustrations depicting various processing operations inprocess 330. In an embodiment, process 330 may be beneficial when thehalogenating agent is not able to fully convert the unexposed regions ofthe photoresist into a volatile byproduct. Particularly, process 330further comprises vaporizing a protonated ligand into the vacuum chamberto convert unexposed regions of the photoresist into a volatilebyproduct.

In an embodiment, process 330 may begin with operation 331, whichcomprises providing a substrate with a metal oxo photoresist. In anembodiment, the substrate and metal oxo photoresist may be substantiallysimilar to the substrate and metal oxo photoresist described above withrespect to operation 121 of process 120.

In an embodiment, process 330 may continue with operation 332, whichcomprises exposing portions of the metal oxo photoresist to createexposed regions and unexposed regions. In an embodiment, the exposureprocess of operation 332 may be substantially similar to the exposureprocess of operation 122 of process 120. FIG. 4A provides across-sectional illustration of the substrate 461 and exposed regions ofthe photoresist 462 _(E) and unexposed regions of the photoresist 462_(U).

In an embodiment, process 330 may continue with operation 333, whichcomprises placing the substrate into a vacuum chamber. The vacuumchamber used in process 330 may be substantially similar to the vacuumchamber used in process 120.

In an embodiment, process 330 may continue with operation 334, whichcomprises vaporizing a halogenating agent into the vacuum chamber. In anembodiment, the halogenating agent may react with the unexposed regionsof the photoresist 462 _(U) to provide a non-volatile product 462 _(U)′.That is, in some embodiments, the halogenating agent, by itself, is notable to fully convert the unexposed regions of the photoresist 462 _(U)into a volatile product that is removable from the vacuum chamber. Inother embodiments, the halogenating agent may react with the exposedregions 462 _(E) to produce a non-volatile product. In an embodiment,the non-volatile product 462 _(U)′ may be a metal halide or a metal oxyhalide with a chemical formula of MX_(x) or MO_(y)X_(x), where M is ametal or semimetal, X is a halide, x is 1-6 and y is 1-5.

In an embodiment, the halogenating agent is a metal halide with aformula MX_(a) or MX_(a)L_(b), where M is a metal or semimetal (e.g.,Mo, W, Ta, Nb, Sn, V, Ti, or Si), X is a halide (e.g., Cl or Br), L is avolatile ligand (e.g., alkyls ethylenediamine, or Cp), a is 1-6 and b is1-5. For example, the metal halide may comprise MoCl₅, TaCl₅, NbCl₅ orWCl₅.

In an additional embodiment, the halogenating agent is a metal oxyhalide with a formula MO_(a)X_(b) or MO_(a)X_(b)L_(c), where M is ametal or semimetal (e.g., Mo, W, Ta, Nb, Sn, V, Ti, or Si), X is ahalide (e.g., Cl or Br), L is a volatile ligand (e.g., alkylsethylenediamine, or Cp), a is 1-5, b is 1-5, and c is 1-5. For example,the metal oxy halide may comprise MoOCl₄, MoO₂Cl₂, WOCl₄, or WO₂Cl₂.

In yet another additional embodiment, the halogenating agent may be anorganic halogenating agent. For example, the halogenating agent maycomprise thionyl chloride (SOCl₂), methanesulfonyl chloride (CH₃SO₂Cl),trichloromethanesulfonyl chloride (CCl₃SO₂Cl), 4-toluenesulfonylchloride (tosyl chloride), oxalyl chloride (ClCOCOCl), tert-butylhypochlorite ((CH₃)₃COCl), N-chlorophthalimide,1,3-dichloro-5,5-dimethylhydantoin, trimethylsilyl chloride, HCl, Cl₂,PCl₅, BCl₃, HBr, Br₂, CCl₃Br, CBr₄,1,2-dibromo-1,1,2,2-tetrachloroethane (Cl₂CBrCBrCl₂), BBr₃, PBr₃,N-bromosuccinimide, N-bromoacetamide,2-bromo-2-cyano-N,N-dimethylacetamide,1,3-dibromo-5,5-dimethylhydantoin,2,4,4,6-tetrabromo-2,5-cyclohexadienone, or trimethylsilyl bromide.

In an embodiment, the halogenating agent may be diluted with an inertgas. For example, inert gases such as Ar, N₂, or He may be used todilute the halogenating agent. In an embodiment, the pressure may bebetween approximately 1 torr and approximately 100 torr. In a particularembodiment, the pressure may be between approximately 5 torr andapproximately 10 torr. In an embodiment, the substrate 461 may have acontrolled temperature during operation 334. For example, thetemperature may vary between approximately 0° C. and approximately 500°C. In a particular embodiment, the temperature may vary betweenapproximately 50° C. and approximately 150° C.

In an embodiment, process 330 may continue with operation 335, whichcomprises purging the vacuum chamber with an inert purge. In anembodiment, the purging process removes any byproducts and unreactedhalogenating agent.

In an embodiment, process 330 may continue with operation 336, whichcomprises vaporizing a ligand into the vacuum chamber. In an embodiment,the ligand reacts with the non-volatile product 462 _(U)′ to produce avolatile byproduct. That is, the reaction between the vaporized ligandand the non-volatile product 462 _(U)′ results in the removal of theunexposed regions from the substrate 461, as shown in FIG. 4C. In caseswhen the non-volatile product is generated from the exposed regions 462_(E), the exposed regions may be removed from the substrate 461. In anembodiment, the ligand is a protonated ligand, such as amine. In anembodiment, the ligand may be diluted with an inert gas such as Ar, N₂,or He. In an embodiment, the volatile byproduct may have the chemicalformula MX_(x)L_(y) or MO_(x)X_(y)L_(z), where M is a metal or semimetal(e.g., Mo, W, Ta, Nb, Sn, V, Ti, or Si), X is a halide (e.g., Cl or Br),L is a volatile ligand (e.g., amine), x is 1-5, y is 1-5, and z is 1-5.

In an embodiment, the pressure may be between approximately 1 torr andapproximately 100 torr. In a particular embodiment, the pressure may bebetween approximately 5 torr and approximately 10 torr. In anembodiment, the substrate 461 may have a controlled temperature duringoperation 336. For example, the temperature may vary betweenapproximately 0° C. and approximately 500° C. In a particularembodiment, the temperature may vary between approximately 50° C. andapproximately 150° C.

In an embodiment, process 330 may continue with operation 337, whichcomprises purging the vacuum chamber. Purging with an inert gas mayresult in the removal of volatile byproducts and remaining vaporizedligands.

In an embodiment, operations 334-337 may define a cycle. The cycle maybe repeated any number of times in order to fully (or substantially)remove the unexposed regions 462 _(U) of the metal oxo photoresist. Forexample, a cycle may comprise a sequence including a pulse of avaporized halogenating agent being introduced into the vacuum chamber,followed by an inert purge, followed by a pulse of a vaporized ligandbeing introduced into the vacuum chamber, followed by an inert purge. Inother embodiments, a single cycle may be used. In such embodiments, asoak of the vaporized halogenating agent may be introduced into thevacuum chamber, followed by an inert purge, followed by a soak of avaporized ligand into the vacuum chamber, followed by an inert purge.

Generally, it has been shown that the etch selectivity of the unexposedregions of the photoresist 462 _(U) relative to the exposed regions ofthe photoresist 462 _(E) increases with increases in pressure.Additionally, it has been generally shown that increased substratetemperatures during one or more of operations 334-337 provide anincrease in the etch selectivity of the unexposed regions of thephotoresist 462 _(U) relative to the exposed regions of the photoresist462 _(E).

Referring now to FIG. 5 , a flowchart describing a process 540 forpatterning a metal oxo photoresist is shown, in accordance with anembodiment of the present disclosure. FIGS. 6A-6B are correspondingcross-sectional illustrations depicting various processing operations inprocess 540. In an embodiment, process 540 may be similar to the process120, with the exception that the halogenating agent is replaced with avaporized organic acid. That is, an organic acid is vaporized to avacuum chamber, where the organic acid reacts with either the unexposedor exposed regions of the metal oxo photoresist to produce a volatilebyproduct.

In an embodiment, process 540 may begin with operation 541, whichcomprises providing a substrate with a metal oxo photoresist. In anembodiment, the substrate and metal oxo photoresist may be substantiallysimilar to the substrate and metal oxo photoresist described above withrespect to operation 121 of process 120.

In an embodiment, process 540 may continue with operation 542, whichcomprises exposing portions of the metal oxo photoresist to createexposed regions and unexposed regions. In an embodiment, the exposureprocess of operation 542 may be substantially similar to the exposureprocess of operation 122 of process 120. FIG. 6A provides across-sectional illustration of the substrate 661 and exposed regions ofthe photoresist 662 _(E) and unexposed regions of the photoresist 662_(U).

In an embodiment, process 540 may continue with operation 543, whichcomprises placing the substrate into a vacuum chamber. The vacuumchamber used in process 540 may be substantially similar to the vacuumchamber used in process 120.

In an embodiment, process 540 may continue with operation 544, whichcomprises vaporizing an organic acid into the vacuum chamber. In anembodiment, the organic acid reacts with either the unexposed regions662 _(U) or the exposed regions 662 _(E) to produce a volatilebyproduct. That is, the reaction between the organic acid and theunexposed regions 662 _(U) results in the removal of the unexposedregions 662 _(U) from the substrate 661 (as shown in FIG. 6B), or thereaction between the organic acid and the exposed regions 662 _(E)results in the removal of the exposed regions 662 _(E) from thesubstrate 661.

In an embodiment, the organic acid may be a carboxylic acid with achemical formula RCO₂H. For example, R may be H, CH₃, tBu, or iPr. In anembodiment, the byproduct of the reaction is a volatile carboxylate. Forexample, the carboxylate may have a chemical formula M(RCO₂)_(x), whereM is the metal from the metal oxo photoresist and R is the R used in theorganic acid.

In an embodiment, the organic acid may be diluted with an inert gas. Forexample, inert gases such as Ar, N₂, or He may be used to dilute theorganic acid. Generally, it has been shown that the etch selectivity ofthe unexposed regions of the photoresist 262 _(U) relative to theexposed regions of the photoresist 262 _(E) increases with increases inpressure. In an embodiment, the pressure may be between approximately 1torr and approximately 100 torr. In a particular embodiment, thepressure may be between approximately 5 torr and approximately 10 torr.

In an embodiment, the substrate 661 may have a controlled temperatureduring operation 544. For example, the temperature may vary betweenapproximately 0° C. and approximately 500° C. In a particularembodiment, the temperature may vary between approximately 50° C. andapproximately 150° C. Generally, it has been shown that increasedsubstrate temperatures provide an increase in the etch selectivity ofthe unexposed regions of the photoresist 662 _(U) relative to theexposed regions of the photoresist 662 _(E).

In an embodiment process 540 may continue with operation 545 whichcomprises purging the vacuum chamber. Purging the vacuum chamber removesthe byproducts from the reaction in operation 544 from the vacuumchamber. In an embodiment, operation 544 may be implemented as a soakfollowed by a single purge in operation 545. In alternative embodiments,operations 544 and 545 may define a cycle comprising a pulse of theorganic acid followed by a purge. In such embodiments, a plurality ofcycles may be repeated in order to clear the unexposed regions of thephotoresist 662 _(U).

Accordingly, embodiments described herein include thermal vapor phaseprocesses for developing a metal oxo photoresist. As such, embodimentsdisclosed herein may not require vacuum chambers with the ability toform a plasma. The removal of a plasma process also reduces damage tothe metal oxo photoresist. This is especially beneficial at lowphotoresist thicknesses (e.g., at photoresist thicknesses ofapproximately 15 nm or smaller). At low photoresist thicknesses plasmadamage may result in poor LER/LWR or even broken line patterns when thepattern is transferred into the underlayer.

Additionally, wet chemistries are avoided, and byproducts generated bythe reactions disclosed herein may be destroyed with abatement systemstypical of the semiconductor manufacturing industry. As such, wastestreams are significantly reduced. Furthermore, vapor phase processesallow for fewer defects and impurities in the resulting developed metaloxo photoresist, especially at small feature sizes, since wetchemistries are not used.

FIG. 7 is a schematic of a vacuum chamber configured to develop theunexposed regions of a metal oxo photoresist, in accordance with anembodiment of the present disclosure. Vacuum chamber 700 includes agrounded chamber 705. In an embodiment, the chamber 705 may betemperature controlled. That is, walls of the chamber 705 may beactively cooled or heated during processes disclosed herein. A substrate710 is loaded through an opening 715 and positioned on a temperaturecontrolled pedestal 720.

Process gases, are supplied from gas sources 744 through respective massflow controllers 749 to the interior of the chamber 705. In certainembodiments, a gas distribution plate 735 provides for distribution ofprocess gases 744, such as, for example, halogenating agents, ligands,organic acids, and/or inert gases. Chamber 705 is evacuated via anexhaust pump 755.

The vacuum chamber 700 is controlled by controller 770. The controller770 may comprise a CPU 772, a memory 773, and an I/O interface 774. TheCPU 772 may execute processing operations within the vacuum chamber 700in accordance with instructions stored in the memory 773. For example,one or more processes such as processes 120, 330, and 540 describedabove may be executed in the vacuum chamber by the controller 770.

While the vacuum chamber 700 is described above as not having featuressuitable for forming a plasma within the chamber, it is to beappreciated that embodiments of the present disclosure may beimplemented in a vacuum chamber 700 that is capable of generating aplasma within the chamber.

FIG. 8 illustrates a diagrammatic representation of a machine in theexemplary form of a computer system 800 within which a set ofinstructions, for causing the machine to perform any one or more of themethodologies described herein, may be executed. In alternativeembodiments, the machine may be connected (e.g., networked) to othermachines in a Local Area Network (LAN), an intranet, an extranet, or theInternet. The machine may operate in the capacity of a server or aclient machine in a client-server network environment, or as a peermachine in a peer-to-peer (or distributed) network environment. Themachine may be a personal computer (PC), a tablet PC, a set-top box(STB), a Personal Digital Assistant (PDA), a cellular telephone, a webappliance, a server, a network router, switch or bridge, or any machinecapable of executing a set of instructions (sequential or otherwise)that specify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines (e.g., computers) that individuallyor jointly execute a set (or multiple sets) of instructions to performany one or more of the methodologies described herein.

The exemplary computer system 800 includes a processor 802, a mainmemory 804 (e.g., read-only memory (ROM), flash memory, dynamic randomaccess memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM(RDRAM), etc.), a static memory 806 (e.g., flash memory, static randomaccess memory (SRAM), MRAM, etc.), and a secondary memory 818 (e.g., adata storage device), which communicate with each other via a bus 830.

Processor 802 represents one or more general-purpose processing devicessuch as a microprocessor, central processing unit, or the like. Moreparticularly, the processor 802 may be a complex instruction setcomputing (CISC) microprocessor, reduced instruction set computing(RISC) microprocessor, very long instruction word (VLIW) microprocessor,processor implementing other instruction sets, or processorsimplementing a combination of instruction sets. Processor 802 may alsobe one or more special-purpose processing devices such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), a digital signal processor (DSP), network processor, or thelike. Processor 802 is configured to execute the processing logic 826for performing the operations described herein.

The computer system 800 may further include a network interface device808. The computer system 800 also may include a video display unit 810(e.g., a liquid crystal display (LCD), a light emitting diode display(LED), or a cathode ray tube (CRT)), an alphanumeric input device 812(e.g., a keyboard), a cursor control device 814 (e.g., a mouse), and asignal generation device 816 (e.g., a speaker).

The secondary memory 818 may include a machine-accessible storage medium(or more specifically a computer-readable storage medium) 832 on whichis stored one or more sets of instructions (e.g., software 822)embodying any one or more of the methodologies or functions describedherein. The software 822 may also reside, completely or at leastpartially, within the main memory 804 and/or within the processor 802during execution thereof by the computer system 800, the main memory 804and the processor 802 also constituting machine-readable storage media.The software 822 may further be transmitted or received over a network820 via the network interface device 808.

While the machine-accessible storage medium 832 is shown in an exemplaryembodiment to be a single medium, the term “machine-readable storagemedium” should be taken to include a single medium or multiple media(e.g., a centralized or distributed database, and/or associated cachesand servers) that store the one or more sets of instructions. The term“machine-readable storage medium” shall also be taken to include anymedium that is capable of storing or encoding a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present disclosure. The term“machine-readable storage medium” shall accordingly be taken to include,but not be limited to, solid-state memories, and optical and magneticmedia.

In accordance with an embodiment of the present disclosure, amachine-accessible storage medium has instructions stored thereon whichcause a data processing system to perform a method of developing a metaloxo photoresist on a substrate with vapor phase processes. The methodincludes exposing a metal oxo photoresist to provide exposed andunexposed regions, and placing a substrate with the exposed photoresistinto a vacuum chamber. In an embodiment, a gas reactive to the unexposedregions of the photoresist is vaporized into the vacuum chamber. Forexample, the reactive gas may comprise one or more of a halogenatingagent, a ligand, and an organic acid. The reactive gas and the unexposedregions of the metal oxo photoresist react to form a volatile byproduct.The byproduct may be removed from the chamber with an inert gas purge.

Thus, methods for forming a developing a metal oxo photoresist usingvapor phase processes have been disclosed.

What is claimed is:
 1. A method of developing a metal oxo photoresist,comprising: providing a substrate with the metal oxo photoresist into avacuum chamber, wherein the metal oxo photoresist comprises exposedregions and unexposed regions; vaporizing a halogenating agent into thevacuum chamber, wherein the halogenating agent reacts with either theunexposed regions or the exposed regions to produce a volatilebyproduct; and purging the vacuum chamber.
 2. The method of claim 1,wherein the halogenating agent comprises a metal halide with a formulaMX_(a) or MX_(a)L_(b), wherein M is a metal or semimetal including oneor more of Mo, W, Ta, Nb, Sn, V, Ti, and Si, wherein X is a halideincluding one or more of Cl and Br, and wherein L is a ligand includingone or more of an alkyl, an ethylenediamine, and Cp.
 3. The method ofclaim 2, wherein the halogenating agent comprises MoCl₅, TaCl₅, NbCl₅,or WCl₅.
 4. The method of claim 2, wherein a is 1-6 and wherein b is1-5.
 5. The method of claim 1, wherein the halogenating agent comprisesa metal oxy halide with a formula of MO_(a)X_(b) or MO_(a)X_(b)L_(c),wherein M is a metal or semimetal including one or more of Mo, W, Ta,Nb, Sn, V, Ti, or Si, wherein X is a halide including one or more of Cland Br, and wherein L is a ligand including one or more of an alkyl, anethylenediamine, or Cp.
 6. The method of claim 5, wherein thehalogenating agent comprises MoOCl₄, MoO₂Cl₂, WOCl₄, or WOCl₂.
 7. Themethod of claim 5, wherein a is 1-5, b is 1-5, and c is 1-5.
 8. Themethod of claim 1, wherein the halogenating agent is an organichalogenating agent.
 9. The method of claim 8, wherein the halogenatingagent comprises thionyl chloride (SOCl₂), methanesulfonyl chloride(CH₃SO₂Cl), trichloromethanesulfonyl chloride (CCl₃SO₂Cl),4-toluenesulfonyl chloride (tosyl chloride), oxalyl chloride (ClCOCOCl),tert-butyl hypochlorite ((CH₃)₃COCl), N-chlorophthalimide,1,3-dichloro-5,5-dimethylhydantoin, trimethylsilyl chloride, HCl, Cl₂,PCl₅, BCl₃, HBr, Br₂, CCl₃Br, CBr₄,1,2-dibromo-1,1,2,2-tetrachloroethane (Cl₂CBrCBrCl₂), BBr₃, PBr₃,N-bromosuccinimide, N-bromoacetamide,2-bromo-2-cyano-N,N-dimethylacetamide,1,3-dibromo-5,5-dimethylhydantoin,2,4,4,6-tetrabromo-2,5-cyclohexadienone, or trimethylsilyl bromide. 10.The method of claim 1, wherein the halogenating agent comprises one ormore of SOBr₂ (thionyl bromide), SO₂Cl₂ (sulfuryl chloride), and SO₂Br₂(sulfuryl bromide).
 11. The method of claim 1, wherein the halogenatingagent is diluted with an inert gas.
 12. A method of developing a metaloxo photoresist, comprising: providing a substrate with the metal oxophotoresist into a vacuum chamber; vaporizing a halogenating agent intothe vacuum chamber, wherein the halogenating agent reacts with the metaloxo photoresist to produce a volatile byproduct; and purging the vacuumchamber, wherein the halogenating agent comprises a metal halide or ametal oxy halide.
 13. The method of claim 12, wherein the halogenatingagent comprises a metal halide with a formula MX_(a) or MX_(a)L_(b),wherein M is a metal or semimetal including one or more of Mo, W, Ta,Nb, Sn, V, Ti, and Si, wherein X is a halide including one or more of Cland Br, and wherein L is a ligand including one or more of an alkyl, anethylenediamine, and Cp.
 14. The method of claim 12, wherein thehalogenating agent comprises a metal oxy halide with a formula ofMO_(a)X_(b) or MO_(a)X_(b)L_(c), wherein M is a metal or semimetalincluding one or more of Mo, W, Ta, Nb, Sn, V, Ti, or Si, wherein X is ahalide including one or more of Cl and Br, and wherein L is a ligandincluding one or more of an alkyl, an ethylenediamine, or Cp.
 15. Amethod of developing a metal oxo photoresist, comprising: providing asubstrate with the metal oxo photoresist into a vacuum chamber;vaporizing a halogenating agent into the vacuum chamber, wherein thehalogenating agent reacts with the metal oxo photoresist to produce anon-volatile product; vaporizing a ligand into the vacuum chamber,wherein the ligand reacts with the non-volatile product to produce avolatile byproduct; and purging the vacuum chamber.
 16. The method ofclaim 15, wherein the halogenating agent comprises a metal halide. 17.The method of claim 15, wherein the halogenating agent comprises a metaloxy halide.
 18. The method of claim 15, wherein the halogenating agentis an organic halogenating comprising thionyl chloride (SOCl₂),methanesulfonyl chloride (CH₃SO₂Cl), trichloromethanesulfonyl chloride(CCl₃SO₂Cl), 4-toluenesulfonyl chloride (tosyl chloride), oxalylchloride (ClCOCOCl), tert-butyl hypochlorite ((CH₃)₃COCl),N-chlorophthalimide, 1,3-dichloro-5,5-dimethylhydantoin, trimethylsilylchloride, HCl, Cl₂, PCl₅, BCl₃, HBr, Br₂, CCl₃Br, CBr₄,1,2-dibromo-1,1,2,2-tetrachloroethane (Cl₂CBrCBrCl₂), BBr₃, PBr₃,N-bromosuccinimide, N-bromoacetamide,2-bromo-2-cyano-N,N-dimethylacetamide,1,3-dibromo-5,5-dimethylhydantoin,2,4,4,6-tetrabromo-2,5-cyclohexadienone, or trimethylsilyl bromide. 19.The method of claim 15, wherein the ligand is a protonated ligand,comprising an amine.